Method and article of manufacture for micro-lens resulting from multi-stage fabrication technique

Abstract

Micro-lenses are formed on the surface of a semiconductive circuit through a plurality of processing stages. In each stage, an alternate lens placement pattern is imparted onto micro-lens suitable material. Unwanted material is removed and micro-lenses are formed from the remaining material. Subsequent stages are applied until all desired micro-lenses in a structure are defined and formed from alternate placement patterns.

What is claimed is:  
     
         1 . A method for depositing micro-lenses on a semiconductive circuit comprising the steps of: 
 successively applying a plurality of coats of micro-lens suitable material to the surface of a semiconductive circuit wherein the current coat is imparted with a succeeding one of a plurality of lens formation patterns;    removing unwanted portions of the current coat of micro-lens suitable material; and    forming a plurality of micro-lenses from the remaining portion of the current coat of micro-lens suitable material.    
     
     
         2 . The method of  claim 1  wherein the step of imparting the current coat with one of a plurality of lens formation patterns is accomplished by: 
 placing a formation mask that embodies one of the plurality of lens formation patterns proximate to the current coat of micro-lens suitable material; and  
 aligning the formation mask to the semiconductive circuit;  
 irradiating the formation mask.  
 
     
     
         3 . The method of  claim 1  wherein the plurality of lens formation patterns are alternate counterparts of each other.  
     
     
         4 . A method for depositing micro-lenses on a semiconductive circuit comprising the steps of: 
 applying a first coat of micro-lens suitable material to the surface of a semiconductive circuit;    imparting a first lens formation pattern onto the first coat of micro-lens suitable material;    removing unwanted portions of the first coat of micro-lens suitable material;    forming a first plurality of micro-lenses from the remaining first coat of microlens suitable material;    applying a second coat of micro-lens suitable material to the semiconductive circuit;    imparting a second lens formation pattern to the second coat of micro-lens suitable material;    removing unwanted portions of the second coat of photo-resist; and    forming a second plurality of micro-lenses from the remaining second coat of micro-lens suitable material.    
     
     
         5 . The method of  claim 4  wherein the first and second lens formation patterns are alternate counterparts of each other.  
     
     
         6 . The method of  claim 5  wherein the first and second lens formation patterns comprise rectangular regions in a checkerboard pattern.  
     
     
         7 . The method of  claim 6  wherein rectangular regions comprise broken corners to avoid continuity with neighboring regions.  
     
     
         8 . The method of  claim 4  wherein the step of forming the first and second plurality of micro-lenses comprise the steps of: 
 raising the temperature of the micro-lens suitable material in order to relieve the surface tension thereof;  
 allowing the micro-lens suitable material to reflow in order to achieve a desired lens focal length; and  
 reducing the temperature of the micro-lens suitable material in order to preserve the achieved lens focal length.  
 
     
     
         9 . The method of  claim 1  wherein the step of applying the first and second coats of micro-lens suitable material comprise the step of spin coating a micro-lens suitable material onto the semiconductive circuit.  
     
     
         10 . The method of  claim 1  wherein the step of imparting the a first lens formation pattern onto the first coat of micro-lens suitable material comprises the steps of: 
 placing a first formation mask comprising the first lens formation pattern proximate to the first coat of micro-lens suitable material;  
 aligning the first formation mask relative to the semiconductive circuit; and  
 illuminating the first formation mask with radiation.  
 
     
     
         11 . A method for depositing micro-lenses on a semiconductive circuit comprising the steps of: 
 applying a first coat of micro-lens suitable material to the surface of the semiconductive circuit;    imparting a first lens formation pattern onto the first coat of micro-lens suitable material;    removing unwanted portions of the first coat of micro-lens suitable material;    applying a second coat of micro-lens suitable material to the to the surface of the semiconductive circuit;    imparting a second lens formation pattern onto the second coat of micro-lens suitable material;    removing unwanted portions of the second coat of micro-lens suitable material; and    forming a plurality of micro-lenses from the remaining portions of the first and second coats of micro-lens suitable material.    
     
     
         12 . A micro-lens structure comprising: 
 plurality of micro-lenses disposed proximate to radiation sensitive active regions formed in a semiconductive circuit located wherein each active region is formed within a boundary region perimeter and    wherein each micro-lens is formed from an island of micro-lens suitable material deposited onto the surface of the semiconductive circuit and wherein each island of micro-lens suitable material occupies an area within the boundary region larger than a resolution setback relative to the perimeter of the boundary region.    
     
     
         13 . The micro-lens structure of  claim 12  wherein the islands of micro-lens suitable material are deposited onto the surface of the semiconductive material and wherein the micro-lenses are formed by: 
 successively applying a plurality of coats of micro-lens suitable material to the surface of a semiconductive circuit wherein the current coat is imparted with one of a plurality of lens formation patterns;  
 removing unwanted portions of the current coat of micro-lens suitable material; and  
 forming a plurality of micro-lenses from the remaining portion of the current coat of micro-lens suitable material.  
 
     
     
         14 . The micro-lens structure of  claim 13  wherein the step of imparting the current coat with one of a plurality of lens formation patterns is accomplished by: 
 placing a formation mask that embodies one of the plurality of lens formation patterns proximate to the current coat of micro-lens suitable material; and  
 aligning the formation mask to the semiconductive circuit;  
 irradiating the formation mask.  
 
     
     
         15 . The method of  claim 13  wherein the plurality of lens formation patterns are alternate counterparts of each other.  
     
     
         16 . The micro-lens structure of  claim 12  wherein the islands of micro-lens suitable material are deposited onto the surface of the semiconductive material and wherein the micro-lenses are formed by: 
 applying a first coat of micro-lens suitable material to the surface of the semiconductive circuit;  
 imparting a first lens formation pattern onto the first coat of micro-lens suitable material;  
 removing unwanted portions of the micro-lens suitable material;  
 forming a first plurality of micro-lenses from the remaining portion of the first coat of micro-lens suitable material;  
 applying a second coat of photo-resist to the semiconductive circuit;  
 imparting a second lens formation pattern onto the second coat of micro-lens suitable material;  
 removing unwanted portions of the micro-lens suitable material; and  
 forming a second plurality of micro-lenses from the remaining portion of the second coat of micro-lens suitable material.  
 
     
     
         17 . The micro-lens structure of  claim 16  wherein application of the first and second coats of from the remaining portion of the first coat of micro-lens suitable material is accomplished through a spin coating process.  
     
     
         18 . The micro-lens structure of  claim 16  wherein the imparting of a first lens formation pattern onto the first coat of micro-lens suitable material is accomplished by: 
 placing a first formation mask comprising the first lens formation pattern proximate to the first coat of micro-lens suitable material;  
 aligning the first formation mask relative to the semiconductive circuit; and  
 illuminating the first formation mask with radiation.  
 
     
     
         19 . The micro-lens structure of  claim 16  wherein the first and second lens formation patterns are alternate counterparts of each other.  
     
     
         20 . The micro-lens structure of  claim 19  wherein the first and second lens formation patterns comprise rectangular regions in a checkerboard pattern.  
     
     
         21 . The micro-lens structure of  claim 20  wherein rectangular regions comprise broken corners to avoid continuity with neighboring regions.  
     
     
         22 . The method of  claim 12  wherein the micro-lenses are formed by: 
 raising the temperature of the islands of micro-lens suitable material in order to relieve the surface tension thereof;  
 allowing the islands of micro-lens suitable material to reflow in order to achieve a desired lens focal length; and  
 reducing the temperature of the islands of micro-lens suitable material in order to preserve the achieved lens focal length.  
 
     
     
         23 . A semiconductive circuit image sensor comprising: 
 surface;    plurality of radiation sensitive active regions disposed in the surface wherein each active regions is encompassed by a boundary perimeter;    sensing circuitry to sense the state of the plurality of active regions; and    plurality of micro-lenses disposed proximate to and coincident with the plurality of active regions    wherein each micro-lens is formed from an island of micro-lens suitable material deposited onto the surface of the semiconductive circuit and    wherein each island of micro-lens suitable material occupies an area within the boundary region larger than a resolution setback relative to the perimeter of the boundary region.    
     
     
         24 . The micro-lens structure of  claim 23  wherein the islands of micro-lens suitable material are deposited onto the surface of the semiconductive material and wherein the micro-lenses are formed by: 
 successively applying a plurality of coats of micro-lens suitable material to the surface of a semiconductive circuit wherein the current coat is imparted with one of a plurality of lens formation patterns;  
 removing unwanted portions of the current coat of micro-lens suitable material; and  
 forming a plurality of micro-lenses from the remaining portion of the current coat of micro-lens suitable material.  
 
     
     
         25 . The micro-lens structure of  claim 24  wherein the step of imparting the current coat with one of a plurality of lens formation patterns is accomplished by: 
 placing a formation mask that embodies one of the plurality of lens formation patterns proximate to the current coat of micro-lens suitable material; and  
 aligning the formation mask to the semiconductive circuit;  
 irradiating the formation mask.  
 
     
     
         26 . The method of  claim 24  wherein the plurality of lens formation patterns are alternate counterparts of each other.  
     
     
         27 . The semiconductive image sensor of  claim 23  wherein the islands of micro-lens suitable material are deposited onto the surface of the semiconductive material and wherein the micro-lenses are formed by: 
 applying a first coat of micro-lens suitable material to the surface of the semiconductive circuit;  
 imparting a first lens formation pattern onto the first coat of the micro-lens suitable material;  
 removing unwanted portions of the first coat of micro-lens suitable material;  
 forming a first plurality of micro-lenses from the remaining portion of the first coat of micro-lens suitable material;  
 applying a second coat of the micro-lens suitable material to the semiconductive circuit;  
 imparting a second lens formation pattern onto the second coat of the microlens suitable material;  
 removing unwanted portions of the second coat of micro-lens suitable material; and  
 forming a second plurality of micro-lenses from the remaining portion of the second coat of micro-lens suitable material.  
 
     
     
         28 . The micro-lens structure of  claim 27  wherein application of the first and second coats of micro-lens suitable material is accomplished through a spin coating process.  
     
     
         29 . The micro-lens structure of  claim 27  wherein imparting a first lens formation pattern onto the first coat of micro-lens suitable material is accomplished by: 
 placing a first lens formation mask comprising the first lens formation pattern proximate to the first coat of micro-lens suitable material;  
 aligning the first lens formation mask relative to the semiconductive circuit; and  
 illuminating the first lens formation mask with radiation.  
 
     
     
         30 . The micro-lens structure of  claim 27  wherein the first and second lens formation patterns are alternate counterparts of each other.  
     
     
         31 . The micro-lens structure of  claim 30  wherein the first and second lens formation patterns comprise rectangular regions in a checkerboard pattern.  
     
     
         32 . The micro-lens structure of  claim 31  wherein rectangular regions comprise broken corners to avoid continuity with neighboring regions.